Managing water resources

Fens Reservoir

We are working with Anglian Water to invest in a new reservoir; to protect your future water supply from climate change, growing demand for water and to enhance the environment.

We want to build resilience in our water supply to prepare for climate change, and continue to further protect and enhance our precious environment; from protecting biodiversity, to minimising risks from drought and flooding, to reducing our carbon footprint to help us on the road to becoming a net zero business.

The Fens Reservoir will do this by providing a reliable supply and store of water for the future, creating new opportunities for the region, to thrive and help to protect our precious chalk streams by reducing abstractions elsewhere. It will also provide new habitats and protected areas for wildlife, create great natural places to explore, and exciting new leisure facilities for people to enjoy. 

Bold new vision for reservoir in the Fens
Cambridge Water and Anglian Water have released an artist’s impression of the proposals for a new reservoir in the Fens. The design has evolved using the valuable feedback from the first phase of consultation and is characterised by its bold ‘ammonite’ shape.

The illustrative image shows how the proposed reservoir could become an exciting new visitor destination, creating jobs and wider economic, environmental, leisure and health benefits for the local community. It also illustrates our aim to create a place that brings people, nature and water together.

The reservoir embankments feature public pathways and exciting landscape forms, with clear potential to host water sports. The design also shows how the reservoir could link to nearby towns and villages and includes wetland areas for wildlife.

We are continuing to engage with landowners, homeowners, local communities and other stakeholders as we develop our proposals.

Fens Reservoir website

Visit the Fens Reservoir website and find out how to give your feedback

Why we need a new reservoir

All of our water comes from the aquifers and other groundwater sources, which can put pressure on the environment, in particular at sensitive sites and when flows are low.

We have identified that there is a need to build new infrastructure to better collect and store water when it is plentiful in the winter periods. (This is water that would normally be sent down river out to sea.) We also want to use our aquifers (huge natural water stores deep underground which fill after periods of rain) in a more sustainable way.

We need to do this because:
  • Our region is one of the fastest growing in the country and that means new homes, which will need a water supply. It is estimated there could be up to 10,000 homes built in the South Cambridge, Cambridge and surrounding areas over the next five years. This reservoir will help provide the extra capacity that Cambridge needs to grow without impacting on the environment.
  • Having the capacity to store more water during periods of greater rainfall through the winter months will also help us reduce the amount of water we need to abstract from underground aquifers during the summer, when it is warmer and there is less rain. This reservoir will allow us to keep hold of more of the water when it rains and use it year round.
  • We operate in the driest region in the UK and, as a result, we are particularly vulnerable to climate change impacts. This reservoir will help protect you from future climate events, including hotter summers and potential future droughts. This will give you confidence that water will there for you whatever the weather.
To deliver this extra capacity, we are investing in a new reservoir in partnership with Anglian Water; the Fens Reservoir. This major project will help to secure a reliable supply of water, and unlock new opportunities for the wider region to thrive.

Photo of a reservoir and a bird on a nestThe new reservoir won’t just make our future water supply more secure. There are a wide range of environmental, social and economic benefits that we know will be created for the region, including:
  • New protected habitats for wildlife, including the possibility of space for new wetlands
  • New visitor parks, footpaths, cycle paths and other natural places, that you can explore not far from Cambridge
  • New leisure destinations with new opportunities for local businesses to start up
We will do all of this with care and attention to protect the environment.

About the new Fens Reservoir

We are working in partnership with Anglian Water to invest in the new reservoir. It will increase water-resource availability by storing high flows from the Great Ouse catchment and release them when needed. Water would be abstracted when river flows allow and will be transferred to the reservoir.

We currently supply an average of 84 million litres of water per day to our 351,000 customers. We anticipate that the reservoir will be able to supply around 100 million litres of water per day into the system to ensure our customers, and customers of Anglian Water, continue to have robust supplies throughout the year.

Quick facts:
It will supply 100 million litres of water per day.
It will have a capacity of 50,000 million litres.
It is also expected that the reservoir will help to enhance local water quality, helping to reduce the risk of flooding in the area and reducing chalk stream abstractions in the Upper Cam catchment.

Photos of girl pond dipping and someone filling a glass of water from a tap
In addition to storing the water we need, the Fens Reservoir could provide many more benefits, including:
  • Improving the environment by taking less water from the aquifer, reducing the pressure on our chalk streams
  • The potential to create new wetlands and habitats for wildlife
  • Creation of meadows and improving woodlands, helping wildlife
  • Creation of new footpaths, cycle paths and nature trails for the local community and other visitors
  • A visitor centre that can be used for recreational activities, school visits, corporate workshops and serve as a community hub
  • The potential for excess water from the reservoir to be provided to agriculture for irrigation
  • Creating a new tourism destination

The planning process and how you can have your say

Delivering the reservoir

Construction of the new reservoir could begin between 2025 and 2030 and could start supplying water to homes by the mid to late 2030s.

In autumn 2022, we announced the proposed location and our assessment on what we will need to do to deliver it responsibly, minimising any impacts on the environment and local communities.

Due to the strategic importance to our future water supply, the project is classified as a Nationally Significant Infrastructure Project (NSIP). These are projects where the UK Government provides the final approval to proceed, including the planning permission and require comprehensive community and stakeholder engagement.

Specific plans for new infrastructure – such as the reservoir we’re proposing – are subject to a development process that is regulated by the Regulators’ Alliance for Progressing Infrastructure Development (RAPID). RAPID was formed to help accelerate the development of new water infrastructure and is made up of the three water regulators Ofwat, the Environment Agency and the Drinking Water Inspectorate.

Plans for new infrastructure need to pass through a series of ‘gateways’ before they can be built. At each gateway, companies submit information about their plans and this is assessed by RAPID to the plans meet the needs of customers. Ofwat also decides whether companies should continue to be allowed funding to continue to investigate and develop their plans to the next gateway.

On 14 November, we submitted our Gate 2 report to RAPID – the Regulatory Alliance for the Progression of Infrastructure Development. RAPID is responsible for reviewing these large new resource options, and ensuring they are on track for delivery, ensuring best value for money for customers and the environment, and will assess whether the project can continue to progress. These documents provide an overview of the project to date and will now be reviewed over the next few months by RAPID.


There are four RAPID gateways in total. 
Graphic of timeline for deliveryOur phase one consultation closed on 21 December 2022. This provided the opportunity to fully understand our proposals and for anyone to provide feedback. 

Feedback is a vital part of the process as we listen to your views and consider how they can help shape the project going forward.

More information

Fens Reservoir website

Visit the Fens Reservoir website for details of the location, maps, plans and how to give feedback.

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